The rotors of dynamoelectric machines contain field windings that produce the magnetic flux which in turn produces the stator current and voltage. Proper cooling of such rotor windings, especially in large generators, is important in order to provide and maintain optimal performance. Direct conductor cooling methods are employed for heat removal purposes in machines of larger ratings. Such direct cooling methods include impressing cooling fluid at the ends of the rotor body whereby the fluid passes into full length subslots for radial discharge along the length of the rotor body by way of radial slots that have been machined or punched through the copper conductors, creepage blocks and wedges included in the rotor slots.
As ratings of such machines increase, the length of the rotor increases requiring corresponding increases in the lengths of the copper coils, creepage blocks, as well as the slot wedges. The slot wedges, which are generally dovetail shaped, are used to maintain the copper coils in place while the rotor is spinning at, for example, 3600 revolutions per minute. In the prior art such coil slot wedges were normally 6 to 12 inches long with a number of such wedges being required for each coil slot, particularly in the longer rotors with high electrical ratings. In an effort to decrease the number of parts that are required for assembly as well as increasing the overall speed of such assembly, full length wedges have been designed and used. In two conventional such arrangements the exemplary wedges are 72 inches and 130 inches long, respectively. Such wedges have conventionally been driven into the slots with a hammer and tamping block. Although the full length wedges have been assembled with relatively little difficulty in the 72 inch long example, the assembly process is nevertheless slow. As to the longer exemplary length, assembly is even slower and somewhat more difficult.
We have discovered that through the use of a specially designed tool attached, for example, to the ventilation holes of such wedges along with a winch using a high strength cable or strap and a tool fixture attached to the rotor shaft, such full length wedges may be pulled into or out of the coil slots relatively quickly and with far less difficulty than in the prior art. Moreover, our assembly/disassembly tool and fixture may be rotated on the rotor shaft coupling, for example, so as to be aligned with any of the coil slots.
We have also discovered that the tool may be attached to the radially inward or outward surfaces of the slot wedges, thus allowing disassembly of wedges whose lengths exceed the distance from the rotor coupling to the slots. That is to say, in the disassembly of very long wedges, the tool and wedge upon being drawn approximately even with the tool fixture at the rotor coupling may be disconnected from the outer surface of the wedge, inverted and connected to the inner surface of the wedge near the rotor slot so that the wedge may be withdrawn further. The process steps are repeated the number of times necessary in order to completely withdraw the wedge from the coil slot.
These and other objects and advantages of the present invention will become apparent upon reference to the following specification, appended claims and drawings.